You have to go to Step 2 in the FILE section.
HOW TO CHANGE OR ENTER BANKING INFORMATION FOR REFUND
You cannot change banking information while your return is in pending, nor can you change it after the return is accepted. The IRS does not allow it.
If you haven't filed your return, follow the steps below
If you have already filed your return and it has been accepted by the IRS for processing you won’t be able to change it. You need to contact the IRS to try to expedite this process. They will put a hold on the direct deposit and issue a paper check instead.
Click on the link below for additional information
What if I entered the wrong bank account for direct deposit?